The Internet is popular as a medium for electronic transactions, for example, transactions between a customer's client computer and a vendor's server computer. With reference to a system (100) shown in FIG. 1, a client computer (105) can establish a network connection with a server computer (115). Once the network connection has been established, the client computer (105) and the server computer (115) can begin to exchange data.
However, network communications are susceptible to security attacks. One type of security attack is known as a man-in-the-middle (MITM) attack. In a MITM attack, a MITM (110) can intercept, relay, view and/or modify data between the client computer (105) and the server computer (115). This type of attack is often invisible to the client computer (105) and the server computer (115), who believe that they are communicating with each other, oblivious to the fact the MITM (110) has compromised their communications.
There is thus a need to improve defenses against a MITM attack.